Oscillograph loading



June 25, 1968 J. Nl-:FF

OSCILLOGRAPH LOADING Filed Feb. 28, 1966 2 Sheets-Sheet l INVENTOR.L/sfx/ J A477 firma/[ June 25, 1968 J. J. NEFF 3,390,398

OSCILLOGRAPH LOADING Filed Feb. 28, 1966 2 Sheets-Sheet 2 K1 'I /WJ '-fv fl/ W W (74' 7? INVENTOR.

United States Patent Oflice 3390398 Patented June 25, 1968 3,390,398OSCILLOGRAPH LOADING Joseph John Neif, Pasadena, Calif., assignor toConsolidated' Electrodynamics Corporation, Pasadena, Calif., acorporafion of California Filed Feb. 28, 1966, Ser. No. 530,524 15Claims. (Cl. 346-68) ABSTRACT OF THE DISCLOSURE A recordng oscillographin which a door and a platen are separately hinged to a frame, theplaten carrying a supply roll of record medium on its reverse side. Thedoor and platen are linked together so that as the door is moved fromits closed position, in which the front side of the platen is disposedadjacent the door, to its open position, the platen moves about itshinge axis to expose the supply roll support to the exterior of theoscillograph for ready and easy loading of a fresh supply roll into theoscillograph. The medium is threaded into the oscillograph merely byunrolling a length of the medium from the roll and by closing the door.

This invention relates to recordng oscillographs having the feature thatopening a door to a housing moves a holder for a roll of .recordmaterial to a position of ready access for rapid replacement of a spentroll with a fresh roll, and closing the door threads the 'recordmaterial in the oscillograph and moves selected components of theoscillograph into an operative recordng interrelation.

A recordng oscillograph is a device for producing upon a record medium agraphic representation, as a function of time, of the instantaneousvalues =of one or more signals applied as inputs to the device. Therecord material usually is a strip of paper which may or may not bespecially prepared, depending upon the nature of the mechanism used toproduce the graphic representation. Basically, however, recordngoscillographs are either optical devices, wherein each input signal isapplied to a galvanometer for deflecting a light beam transversely ofthe path of movement of a photosensitive record medium, or they aremechanical devices wherein each input signal is applied to a motor whichdrives a stylus transversely of the path of movement of the recordmedium. The latter class of oscillographs may incorporate ink-writingstyli, or they may incorporate heat-writing styli cooperating with aheat Sensitive record medium. The present invention is described belowwith relation to a heat-writing mechanical oscillograph, although it hasutility with inkwriting and optical oscillographs.

Recording oscillographs are frequently used in tests and the likewherein it is desired that records be obtained over a long period oftime. Often the supply of record material in the oscillograph isexhausted one or more times during the test, and it becomes necessary toinsert a new supply roll of record material into the instrument beforefurther recordings can be made. The longer the time required to change asupply roll, the more data is lost by reason of nonrecordation, unless astand-by oscillograph is available for use during the period required tochange supply rolls in the principal instrument. Existing recordngoscillographs are so constructed that the roll changing operation is atime consuming and relatively complicated process, and care must betaken that the new strip of record material is properly threaded in theoscillograph. If the record material is not properly threaded, thesignal traces produced by the oscillograph may be illegible, and therecord material may jam in the instrument.

This invention lprovides an improved recordng oscillograph which may beloaded with a supply of record material easily and rapidly. Theoscillograph also has the feature that the record material is threadedinto the instrument automatically upon closure of a door which must beopened before a new supply roll of record material may be inserted intothe instrument. The invention also provides a novel and efiicientmechanism for maintaining uniform tension in the record material acrossits width; such a mechanism is particularly useful in a heat-writingmechanical oscillograph, although it is also useful in inkwritingmechanical oscillographs and optical oscillographs.

In brief but general terms, this invention has utility in anoscillograph for producing upon a moving strip of record material arecord of variations in the magnitude of a signal applied as an input tothe oscillograph. The oscillograph includes a housing having a frame androll support means for receiving and rotatably mounting a roll of therecord material. Record material drive means are provided in the housingfor moving the strip of record material along a selected path in thehousing. The housing also contains writing means to which the signal isapplied and which is operative upon the record material, at a selectedpoint along the path of movement of the record material during operationof the oscillograph, to produce upon the record material a record ofvariations in the magnitude of the signal. A platen is disposed in thehousing and has a surface over which the record material moves duringoperation of the oscillograph. The improvement provided by thisinvention includes a door hingeably mounted to the housing frame formovement relative to the frame between an open position and an operativeclosed position. In its closed position, the door is disposed adjacentto the platen surface; this is the position of the door during'operation of the oscillograph. Bracket means are provided for mountingthe roll support means adjacent the side of the platen which is oppositefrom the platen surface over which the record material moves duringoperation of the oscillograph. Further, the invention includes meanshingeably mounting the platen lto the housing frame for movement of theplaten relative to the frame about an axis adjacent the closed positionof the door. The door carries, for movement with the door, means whichare operative to engage the record material with the `record materialdrive means when the door is in its closed position. Also, the structureprovided by the invention includes means ooupled to the door, andoperable as the door is moved from its closed to its open position, formoving the platen about its hinge axis from a first position of theplaten relative to the writing means to a second position relative tothe writing means. In its first position the platen is disposed inoperative writing relation to the writing means and the drive means isoperable to move the strip of record material along the abovementionedpath. In the second position of the platen, the record supply supportmeans is exposed forrapid loading of a roll of record material into thesupport means, and the record material is threadable along the path bypulling a length of material from the roll and by closing the door toreturn the platen to its first position. Closure of the doorautomatically engages the record material with the drive means.

The above-mentioned and other features of the invention are more fullyset forth in the following description presented with reference to theaccompanying drawings, wherein:

FIG. 1 is a cross-sectional elevation view of a recordling oscillographof the mechanical heat-writing type, the oscillograph being shown in itsrecordng condition;

FIG. 2 is a cross sectional elevation view of the oscillograph 'shown inFIG. 1 disposed in its supply roll reloading conditions;

FIG. 3 is a cross-section view taken along line 3-3 of FIG. l; and

FIG. 4 is a cross-sectional elevation view taken along line 4-4 of FIG.1.

As indicated above, the invention is described below in the context of aheat-writing mechanical oscillograph. The invention may also beincorporated into an ink-writing mechanical oscillograph or into anoptical oscillograph.

A heat-writing mechanical oscillograph includes a housing frame 11having a pair of spaced end plates 12, only one of which is shown. Anaccess door 13 is hingeably mounted at its upper end to the frame by ahinge pin 14. The door is movable through an arc of about 120 between aclosed position (shown in FIG. 1), wherein the door closes the front ofthe housing, and an open position of the door' (shown in FIG. 2). Thedoor is disposed in -its closed position when the oscillograph isoperated for the purpose of recording graphic representations of thevariations in an oscillograph input signal. The door is disposed in itsopen position when it is desired to insert a fresh supply roll ofrecording paper into the ininstrument.

A bank of aligned stylus drive motors 15 (only one of which is visiblein FIGS. 1 and 2) is mounted in the upper rear portion of the housing.The stylus drive motors are mounted to a -motor bracket 16. The motorbracket is mounted to the frame end plates by coaxially aligned pins 17so that the bracket is rotatable relative to the frame about an axis 18.A stop pin 19, having a circumferential rubber tire 20, extends fromeach frame end plate at a location spaced from the adjacent motorbracket hinge pin into abutting engagement with a Vertical flange 21 ateach end of the bracket. The stop pins function tosecure the bracket,and thereby the drive motors, in a predeter-mined postion when the dooris in its closed position. A separate oscillograph input signal isapplied to each drive motor.

Each Stylus drive motor has a rotatable output shaft 22 which extendsgenerally upwardly from the motor to a hub 23 of a stylus support arm24. The motor shafts are aligned parallel to each other. Each Stylus armextends normal to its motor drive shaft toward door 13. At its endremote from its supporting drive motor shaft, each stylus support armcarries a Stylus 25. Each stylus is comprised of a tubular sleeve havinga respective one of a pair of electrical conductors 26 connected to itsopposite ends. When a potential is applied to the opposite ends of thesleeve, the sleeve heats and produces a -mark on a heat Sensitive stripof recording paper which moves past the sleeve. The engagement of thestylus with the recording paper is described below.

A platen assembly 30 is disposed in the housing adjacent the closedposition of door 13. The platen assembly is mounted to the frame endplates by a pair of coaxially aligned hinge pins 31 which are connectedto the frame end plates adjacent the door in its closed position. Eachpin 31 carries a circumferential rubber sleeve 33. The platen assemblyincludes a platen 34 having a planar surface 35 which, when theoscillograph is operating and the door is closed, lies parallel to andadjacent to the inner surface of the door opposite a viewing window 36carried by the door. At its end away from pins 31, the platen is bentaway from surface 35 and, as shown best in FIG. 2, terminates in aknife-edge member 37 having a sharp writing edge 38 spaced remote fromthe pins. The knife-edge member has a convexly contoured drag surface 39adjacent the writing edge; this surface is disposed convex toward thestylus drive motors during operation of the oscillograph. If desired,the knife-edge member may be formed integral with the platen.

A pair of reslient brackets 40 are mounted to the platen at Iitsopposite ends adjacent the frame end plates and extend away from platensurface 35. Each bracket, at a location spaced from the platen,rotatably mounts a respective one of a pair of coaxially aligned recordsupply roll holder pins 41. The pins are sized to fit snugly into a core(not shown) upon which a quantity of heat sensitive record paper 42 iscoiled to form a record paper supply roll 43. An empty core can beremoved from the pins and a full roll mounted on the pins by deflectingthe brackets against their reslient bias tomove the pins away from eachother.

A record paper drive roller 45 is rotatably mounted between the frameend plates below the platen assembly adjacent the closed position ofdoor 13. The drive roller is driven by a motor 46 via a gear train 47 sothat a length of record paper engaged with the roller is pulled fromsupply roll 43, over surface 39 and writing edge 38, and over platensurface 35 to the drive roller during operation of the oscillograph. lnorder that the record paper may be properly engaged with the driveroller during operation of the oscillograph, a pressure roller 48 isrotatably mounted to the inner surface of the door in such position thatthe pressure roller is moved into cooperative engagement with the driveroller when the door is closed. The pressure roller is resilientlybiased toward the drive roller by a biasing vmechanism described below.Record paper moved along the above-described path in the oscillographpasses from between the pressure and drive rollers through an exit slot49. The paper s guided from the drive roller to the slot by a guide 50extending between the frame end plates adjacent the lower portion of thedoor in the closed position of the door.

A record paper drag roller 51 is rotatably mounted between a pair of armassemblies 52 which extend forwardly of the housing from motor bracketend flanges 21. The drag roller is disposed adjacent the knife-edgemember during operation of the oscillograph and is resiliently biased toforce paper passing between it and the knifeedge into engagement withconvexly curved surface 39. This cooperation between the drag roller andthe knifeedge member causes the strip of record paper between the dragand drive rollers to be under a selected amount of tension and to break,i.e., bend, sharply as it is moved over writing edge 38. The tension inthe strip between the drag and drive rollers is essentially Constantsince the amount of platen assembly surface engaged by the strip isessentiallyconstant regardless of the degree of fullness of the papersupply roll.

A lug bracket 55 is secured to door 13 adjacent each frame end plate andadjacent ldoor hinge pin 14. The lug brackets are positioned so thatthey extend toward the motor bracket when the door is closed. Two linkmembers 56 and 57 are pivotally connected to each lug bracket by pins 58and 59, respectively. The ends of link members 55 are pivotallyconnected to the adjacent stylus motor end flanges by pins 60. Pins 60are coaxially aligned with each other and are spaced from motor brackethinge pins 17 so that, when the door is closed, pins 14, 58 and 60 liein a straight line, and so that, when the door is opened, the motorbracket is hinged upwardly through an arc of about 25 about axis 18.Link members 57, at locations spaced from pins 59, are pivotallyconnected to the platen assembly at coaxially aligned locations by pins61. Pins 61 are spaced from platen assembly hinge pins 31 such that,when the door is closed, pins 59 lie toward the stylus motor bracketfrom a line between pins 14 and 61. Link arms 57 extend beyond pins 61and, beyond pins 61, define inclined surfaces 62 which engage tires 32of the platen assembly hinge pins to prevent movement of these linkmembers and of the door during opening of the door beyond a point whichis selected so that pins 58, 59 and 60 and pins 3.1, 59 and 61 areneither in a straight line nor have they moved into and past a straightline during such movement of the door. In other words, surfaces 62engage tires 32 in time to limit the opening movement of the door sothat as the door is moved from its fully open to its closed position notoggle effects are encountered relative to link members 56 or 57.Accordingly, the door cannot jam open.

As shown in FIG. 1, the link members are arranged relative to the platenassembly and the stylus motor bracket so that, when the door is closed,the motor bracket is engaged against stop pins 19 and the surface of theplaten is adjacent to and parallel to door window 36. Also, pressureroller 48 is resiliently engaged with drive roll 45 on the side of thedrive roll opposite from the platen assembly. The heated Stylus carriedby each stylus arm engages record paper 42 at knife edge 38 withessentially point contact. As a result, as the Stylus moves transverselyof the path of movement of the record paper 1n response to an inputsignal applied to the corresponding stylus drive motor, a sharplydefined line or graphic representation of the variations in the signalis produced on the record paper. This record is visible through window36 as the record paper moves over platen surface 35.

Because link member pivot pins 59 lie toward the Stylus motors from aline through pin 14 and pins 61, whereas pins 14, 58 and 60 lie in aline when the door is closed, the first stages of movement of the doorfrom its closed toward its open position causethe platen assem- .bly tomove a slight amount counter-clockwise (as seen have been moved out ofthe path of the knife-edge 'member before this member begins to move outof the housing in response to opening movement of the door. Thissequence of movements is reversed when the door is closed.

As shown in FIG. 2, when the door is fully open, the platen assembly isso positioned that supply roll supporting brackets 40 are readilyaccessible from the exterior of the housing. A spent roll of recordpaperpmay be extracted from the oscillograph and a full roll inserted inits place in a matter of seconds merely by defiecting braclrets 40against their inherent resilient bias which urges pins 41 toward eachother, After a new roll of record paper has been mounted in the platenassembly, a quantity of paper is unrolled from the roll and draped overthe knife-edge member. As the door is closed and the movable componentsof the oscillograph move from the relation shown in PIG. 2 to therelation shown in FIG. 1, this length of record paper moves intoengagement with platen surface 35 and extends past the drive roller. Theportion of the record paper which extends below the drive roller isengaged by pressure roller 48 as the door is closed and is moved by thepressure roller into engagement with the drive roller. After the door isclosed, it is only necessary to operate motor 46 sufificiently to rotatethe drive roller three or four times to cause the record paper to beproperly aligned and tensioned along its path of movement through theoscillograph.

It will be understood that the structure described above may be used toadvantage in an ink-writing mechanical oscillograph. The only basicstructural difference between the structure described and the structureof an ink-writing oscillograph is in the nature of the Stylus carried byeach stylus arm. Such a structural difference, however, is not materialto the present invention. In an optical oscillograph, the stylus andStylus arm combinations are replaced by light beams. In an opticaloscillograph, therefore, use of the invention may result in only theplaten assembly, over 'which a light-Sensitive record paper moves, beingmoved in response to movement of a door so that a roll of record papercarried by the platen assembly may be changed easily and rapidly.

As shown in FIGS. 1 and 3, pressure roller 48 is mounted to door .13 bya pair of arms 65, each of which journals a corresponding one of a pairof roller axles 66 at the end of the arm spaced away from the door. Ad-

jacent its other end, each arm is journalled on a corresponding one of apair of pins 68 carried by the door. An elongate spring rod 69 extendsparallel to the pressure roller between the roller and the door and hasits opposite ends secured to arms 65, as seen best in FIG. 3. Below thepressure roller and centrally of its length, a lug 70 extends rearwardlyfrom door 13. A post 71, prefera'bly provided by an adjustable setscrew, extends upwardly from the lug into essentially point contact withthe spring rod at essentially the midpoint of the distance along the rodbetween arms 65. The post has a length such that, when the pressureroller is engaged with the drive roller, the ends of the spring rod aredeflected away from the drive roller relative to the portion of thespring rod engaged with the post, and arms 65 are biased toward thedrive roller about pins 68. The amount of this bias is determined by thestiffness of the spring rod and the amount of deflection of the springrod. Because the spring rod is not constrained at its midpoint, equalforces are imposed upon arms 65 by the rod and the force of engagementof the pressure roller with the drive roller is equal at each end of thepressure roller. Also, the pressure roller is thus so mounted that anynon-parallelisrn between it and the drive roller is eliminated. If thedoor hinge axis is skew to the axis of the drive roller, the pressureroller is still parallel to the drive roller when the drive and pressurerollers are engaged. As a result, the record paper at all points acossits width is wrapped around the drive roller to the same extent and thedrive roller functions properly to pull the record paper over thewriting edge in such a manner that the tensio'n in the paper across itswidth at the writing edge is uniform. Uniform tension m the record paperat the writing edge means that the lines produced by the action of thestyli upon the paper are of uniform density.

To further assist in maintaining the tension in the record paper uniformacross the length of writing edge 38, drag roller 51 is mounted to thestylus motor bracket by a mechanism similar in principle to themechanism which mounts the pressure roller to the door. As shown in FIG.4, each drag roller mounting arm assembly 52 includes a guide arm whichis rigidly mounted to a corresponding one of bracket fianges 21 byscrews 76. A flange 77 extends downwardly from the motor bracket betweenarms 75 adjacent the front edges of fianges 21. Forwardly of fiange 77,each arm 75 defines an elongate slot 78 (see FIG. 2); a similar slot 79is formed in each arm adjacent its end remote from the stylus motorbracket. A movable arm member 80 is slidably engaged with each of theopposing surfaces of arms 75 forward of fiange 77. A spring rod 81 issupported at its midlength between arm members 80 in a diametral slot 82formed in the forward end of a spring support sleeve S3 mounted at itsrear end to bracket fiange 77. Each end of the spring rod extendsthrough a circular aperture 84 formed in the rear portion of acorresponding arm member 80 into sliding engagement with adjacent slot78. The drag roller has coaXially aligned axles 85 which are rotatablymounted in bearings 86 carried by arm members 80 at their forward ends.Each drag roller axle extends beyond its bearing into engagement with anadjaceht slot 79. Accordingly, the drag roller is mounted for limitedsliding movement toward and away from bracket fiange 77, but is urgedinto engagement with surface 39 of the knfe-edge member by spring 81.

Because only a single spring is used and because the spring is supportedat essentially a single point at its midlength, equal forces are imposedon axles 85 and the pressure of the roller against a strip of recordpaper disposed between it and surface 39 is equal across the width ofthe paper. As a result, the friction Produced between the roller andwriting edge 38 along surface 39 is uniform across the width of thestrip and the angle with which the paper breaks over the writing edge issharp and uniform across the width of the strip. Thus, each stylusengages the record paper at only a single sharply defined 7 point alongthe writing edge and the trace provided by the stylus is uniformregardless of the position of the stylus transversely of the path ofpaper movement.

Also, because of the manner in which the drag roller is mounted andbiased toward surface 39, the advantages described above are obtainedeven though the operational position of the platen assembly relative tothe stylus motor bracket may change slightly during the life of theoscillograph because of Wear in the joints of the linkage assemblyinterconnecting the bracket and the platen assembly with the door.

I claim:

1. In a recording oscillograph including a housing having a frame, meansfor receiving a supply of strip record material, drive means for movinga strip of said record material along a selected path in the housing,writing means in the housing for producing upon the record material arecord of variations in an oscillograph input signal, and a platenhaving a surface over which the record material moves during operationof the oscillograph, the improvement comprising, in combination, a doorhingeably mounted to the housing frame for movement relative to theframe between an open position and an operative closed position adjacentthe platen surface during operation of the oscillograph, means mountingthe record material supply receiving means to the side of the platenopposite from said surface, means hingeably mounting the platen to theframe separate from the door for hingable movement relative to the frameand the door about an axis fixed relative to the frame adjacent the doorin its closed position, means carried by the door for movement therewithoperative to engage the record material with the record material drivemeans in the closed position of the door, and means coupled to the doorand operable in response to movement of the door from its closed to itsopen position for moving the platen about its hinge axis from:

(a) an operative recording relation of the platen relative to thewriting means wherein the drive means is operable to move said recordmaterial along said path, to

(b) a position of the platen wherein the record material supplyreceiving means is exposed for loading a supply of record materialthereinto and the record material is threadable along said path bypulling a length of said material from the supply and closing the doorto return the platen to said operative recording relation and to engagethe record material with the drive means.

2. An oscillograph according to claim 1 including record materialtensioning means mounted for operative engagement with the recordmaterial when the door is in its closed position.

3. An oscillograph according to claim 2 wherein the record materialtensioning means is mounted to engage the record material between theroll support means and the platen surface.

4. An oscillograph according to claim 3 wherein the record materialtensioning means includes a drag roller disposed transversely of thepath of said strip of record material, and means resiliently biasing thedrag roller into the strip moving therepast.

5. An oscillograph according to claim 1 wherein the writing meansincludes a stylus, a stylus drive motor coupled to the stylus for movingthe stylus transversely of the selected path, and means mounting thestylus relative to the platen so that the stylus engages record materialpassing the platen only when the platen is in said operative recordingrelation to the writing means.

6. An oscillograph according to clairn 5 including stylus motor mountingmeans mounting the stylus drive motor to the frame for rotation relativeto the frame about a hinge axis, and the means coupled to the doorincludes means operable in response to movement of the door from itsopen to its closed position for moving the motor mounting means and themotor from a first position wherein the stylus is -located relative tothe platen for engaging record material passng the platen to a secondposition in which the stylus is spaced from the position occupied in itsfirst position.

7. An oscillograph according to claim 6 wherein the means coupled to thedoor includes a rigid link member pivotally connected at one end thereofto the door and at its other end to the stylus motor mounting means.

8. An oscillograph according to claim 7 wherein the locations of pivotalconnection of said link member to the door and to the stylus motormounting means lie in a substantially straight line with the door hingeaxis when the door is in its closed position.

9. An oscillograph according to claim 6 including resilient stop meansabutting the stylus motor mounting means when the door is closed fordefining the first position of the stylus motor mounting means.

10. An oscillograph according to claim 5 wherein the platen defines aconvexl'y contoured drag surface extending transversely of said selectedpath between said platen surface adjacent the door and the location of aroll of said record material, a rotatable drag roller disposed adjacentsaid drag surface so that record material passes between the drag rollerand the drag surface, and means resiliently biasing the drag roller intoengagement With the drag surface.

11. An oscillograph according to claim 10 including stylus motor supportmeans hingeably mounting the stylus lmotor to the frame, means couplingthe stylus motor support means to the door for movement of said supportmeans relative to the frame in response to hinging movement of the door,and wherein the drag roller is carried by the stylus motor support meansfor movement therewith and the means resiliently biasing the drag rollercooperates between the roller and the stylus motor support means.

12. An oscillograph according to claim 1 wherein the means coupled tothe door comprises an elongate substantially rigid link member pivotallyconnected at one end to the door adjacent the hinge axis of the door andpivotally coupled at its other end to the platen at a location oppositethe platen hinge axis from the closed position of the door.

13. An oscillograph according to clairn 12 wherein the door and platenhinge axes and the link member pivot axes are substantially parallel,and the link member is arranged between the door and the platen so thatthe connection of the link member to the door lies opposite the doorfrom a line between the connection of the link member to the platen andthe door hinge axis when the door is in its closed position.

14. An oscillograph according to claim 13 including stop means fordefining the open position of the door such that the pivot axes of thelink member and the platen hinge axis are neither in a straight linerelation in the open position of the door nor have they moved into andout of such relation during movement of the door from its closed to itsopen position.

15. In a recording oscillograph including: a housing having a frame;means for receiving a supply of strip record material; drive means formoving a strip of said record material along a selected path in thehousing; writing means in the housing, including a stylus engageablewith the record material, a drive motor for the stylus, and supportmeans for the stylus motor, for producing upon the record material arecord of variations in an oscillograph input signal; and a platenhaving a surface over which the record material moves during operationof the oscillograph; the improvement comprising, in combination: a doorhingeably mounted to the housing frame for movement relative to theframe between an open position and a closed position; means mounting therecord material supply receiving means to the side of the platenopposite from said surface, means hingeably mounting the platen to theframe for movement relative to the frame and to the door; means carriedby the door for movement therewith operative to engage the recordmaterial with the record material ldrive means in the closed position ofthe door, means hingeably mounting the stylus motor support means to theframe for movement relative to the frame, to the door, and to theplaten; and means coupled to the door and operable in response tomovement of the door from its closed to its open position:

(a) for moving the platen from (1) a position in which the supply ofrecord material is located behind the platen relative to the door andwherein the drive means is operable to move said record material alongthe selected path, to (2) a position of the platen wherein the recordmaterial supply receiving means is exposed for loading a supply ofrecord material thereinto 20 and the record material is threadable alongthe selected path by pulling a length of the record 16 material from thesupply and closing the door to return the platen to its former positionand to engage the record material with the drive means, and (h) formoving the stylus motor support means from (1) a position in which thestylus engages record material moving over the platen along the selectedpath, to

(2) a position in which the Stylus is spaced from the platen and theplaten may move between its positions as aforesaid without engaging thestylus.

References Cited UNITED STATES PATENTS 3,051,408 8/1962 Fineh 346-1363,l54,368 10/1964 Daigler et al 346-68 3,283,335 11/1966 Sachlehen346-68 RICHARD B. WILKINSON, Primary Examiner.

E. C. SIMMON'S, Assistant Examiner.

